Escherichia coli O157 Infection and Hemolytic Uremic Syndrome (HUS), 2012
During 2012, 124 culture-confirmed cases of Escherichia coli O157 infection (2.3 per 100,000 population) were reported. The number of reported cases represents a 9% decrease from the median number of cases reported annually from 2002 to 2011 (median, 137 cases; range, 110 to 163). During 2012, 34 (27%) cases occurred in the metropolitan area. Sixty-seven (54%) cases occurred during May through October. The median age of the cases was 21 years (range, 1 to 72 years). Seventeen percent of the cases were 4 years of age or younger. Thirtynine (31%) cases were hospitalized; the median hospital stay was 4 days (range, 1 to 37 days). No cases died. In addition to the 124 culture-confirmed E. coli O157 cases, 115 cases of Shiga toxin-producing E. coli (STEC) infection were identified in 2012. Of those, culture-confirmation was not possible in 14, and therefore it is unknown if those were O157 or another serogroup. Among the remaining 101 cases of STEC other than O157, E. coli O26 accounted for 39 cases, E. coli O103 for 34, and E. coli O111 for 18. These three serogroups accounted for 90% of all non-O157 STEC cases. Seven E. coli O157 outbreaks were identified during 2012. All seven outbreaks were due to person-to-person transmission in daycares. The seven outbreaks resulted in 38 illnesses (29 culture-confirmed), with a median of 4 cases per outbreak (range, 2 to 10 cases).
Hemolytic Uremic Syndrome (HUS)
In 2012, 13 HUS cases were reported. The number of reported cases is similar to the median number of cases reported annually from 2002 to 2011 (median, 14 cases; range, 10 to 22). In 2012, the median age of HUS cases was 4 years (range, 1 to 86 years); 11 of the 13 cases occurred in children. All 13 cases were hospitalized, with a median hospital stay of 15 days (range, 5 to 40 days). No cases died. From 1997 through 2012, the overall case fatality rate among HUS cases was 5.1%. All 13 HUS cases reported in 2012 were post-diarrheal. E. coli O157:H7 was cultured from the stool of 11 (85%) cases; the remaining 2 (15%) HUS cases were positive for E. coli O157:H7 by serology. In 2012, there were 2 outbreakassociated HUS cases, both associated with person-to-person transmission in daycares.
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